No two same characters (including minor and villains) are of the same race or species.
Downplayed: Everyone is of different nationalities, but Bob and Alice are white, Jack and Velma are black, and Tony is Hispanic.
Justified: The Five-Man Band is some sort of coalition for diversity.
Inverted: Everyone in the group is one race. Everyone else is thoroughly diverse, ethnically, socio-economically, spiritually grammatically...
Everyone in the group looks to be different races, but are all one race.
A group of diverse individuals are seen together, but are actually strangers.
But each have friends that are ethnically diverse.
But then they decide to become friends.
Parodied: There is a scene where the characters specifically pick out diverse friends so they can teach kids about diversity, but they actually are racists.
Zig Zagged: Each friend seems to be a different race, but then they are revealed to be wearing make up to look different, but then they find out that they are actually different races, but then they find out that that's not true...
Only one or two minorities are represented in the group.
The medium is radio and no clues as to ethnicity are ever given.
Enforced: The producers want to appeal to a wide and diverse audience.
Lampshaded: "Statistically, all five of us should be white, since we're from northern Minnesota."
Invoked: Characters intentionally seek out ethnically diverse friends in order to be seen as open minded and tolerant.
Exploited: A Politically Incorrect Villain forces the group together through manipulation in hopes that they will kill each other over racial/cultural/religious tension.
Defied: Characters refuse to be friends with anybody not of their own race.
Discussed: "We all come from different backgrounds but that's no reason why we shouldn't work together."
Conversed: "I understand that the writers want to be diverse but no one has any characteristics beyond their ethnicity."
Implied: Their different skin tones are clearly visible, but this is never mentioned.
Deconstructed': The group is so focused on diversity that they accept members with no real qualifications other than being diverse. This negatively impacts their performance.